using System;
using System.Collections.Generic;
using System.IO;
using System.Text.Json;
using System.Linq;

namespace spplus;

public static class import
{
    public static List<Student> ImportStudentsFromFile(string path)
    {
        var dict = new Dictionary<string, (string Name, List<string> Courses)>();

        foreach (var line in File.ReadLines(path).Skip(1)) // Header überspringen
        {
            if (string.IsNullOrWhiteSpace(line))
                continue;

            var parts = line.Split(',');
            if (parts.Length < 3)
                continue;

            string nameWithId = parts[0].Trim();
            string course = parts[2].Replace("(2)", "").Replace("(3)", "").Replace("(4)", "").Trim();

            int open = nameWithId.LastIndexOf('(');
            int close = nameWithId.LastIndexOf(')');
            if (open < 0 || close < 0 || close <= open)
                continue;

            string name = nameWithId[..open].Trim();
            string id = nameWithId[(open + 1)..close].Trim();

            if (!dict.ContainsKey(id))
                dict[id] = (name, new List<string>());

            dict[id].Courses.Add(course);
        }

        var result = new List<Student>();

        foreach (var (id, data) in dict)
        {
            var student = new Student(id, data.Name, data.Courses);
            result.Add(student);
        }

        return result;
    }
    
    public static List<Student> ImportResultFromFile(string path)
    {
        var dict = new Dictionary<string, string[]>(StringComparer.OrdinalIgnoreCase);

        foreach (var line in File.ReadLines(path).Skip(1)) // Header überspringen
        {
            if (string.IsNullOrWhiteSpace(line))
                continue;

            var parts = line.Split(',', StringSplitOptions.None);
            if (parts.Length < 5)
                continue;

            var studentId = parts[0].Trim();
            dict[studentId] = new[]
            {
                parts[1].Trim(),
                parts[2].Trim(),
                parts[3].Trim(),
                parts[4].Trim()
            };
        }

        return dict
            .Select(entry => new Student(entry.Key, string.Empty, new List<string>())
            {
                Result = entry.Value
            })
            .ToList();
    }

    private sealed class ResultImportEntry
    {
        public int Semester { get; set; }
        public string SportName { get; set; } = string.Empty;
        public List<string> Students { get; set; } = new();
    }

    public static List<(int Semester, CourseCrafter.CourseInstance Instance)> ImportResultFromJson(string path)
    {
        try
        {
            var json = File.ReadAllText(path);
            var entries = JsonSerializer.Deserialize<List<ResultImportEntry>>(json);
            if (entries == null) return new();

            var result = new List<(int Semester, CourseCrafter.CourseInstance Instance)>();

            foreach (var e in entries)
            {
                if (string.IsNullOrWhiteSpace(e.SportName))
                    continue;

                var sport = Settings.Instance.Sports.FirstOrDefault(s =>
                    string.Equals(s.Name, e.SportName, StringComparison.OrdinalIgnoreCase) ||
                    s.AlternativeNames.Any(a => string.Equals(a, e.SportName, StringComparison.OrdinalIgnoreCase)));

                if (sport == null)
                    continue;

                var ci = new CourseCrafter.CourseInstance
                {
                    Sport = sport,
                    Students = e.Students.Distinct().ToList()
                };

                result.Add((e.Semester, ci));
            }

            return result;
        }
        catch
        {
            return new();
        }
    }
}